Markov-based channel characterization for tractable performance analysis in wireless packet networks

An optical packet switch design using optical switching and shared electronic buffering is described and analyzed. The electronic buffering and add/drop unit allows random memory access, variable packet length, and aggregation/segregation of low bit rate streams. The design is scalable to a large number of wavelengths, and employs contention resolution by using the wavelength dimension combined with electronic buffering. The number of buffer inputs, i.e. the number of optoelectronic conversions, is minimized. The packet loss and delay performance when using fixed packet length and electronic buffering are investigated by simulation. If the link utilization is moderate, the buffering requirements becomes minimal. If number of wavelengths in the link is increased, the number of buffer inputs can be reduced. With a sufficiently high number of wavelengths, the buffer requirements is minimal, even when the link utilization is high.

The IEEE 802.16 is a series of telecommunication standards that provides Broadband Wireless Access (BWA) services and has received great attention worldwide. The IEEE 802.16j emerged as a standard in the middle of 2009, specifying the procedure of supporting Mobile Multi-hop Relay (MMR) networks. The use of the “multi-hop” architectures not only requires a re-design of the functional implementations of both physical and link layers, because the topology in such networks is fundamentally different from that of single hop, but also necessitates further investigation of other “non-functional” properties, such as end-to-end packet delay performance, which is one of the Quality of Service (QoS) metrics and is considered to be critical for the future success of multi-hop network deployment. In this paper we report the development of a new Matlab/Simulink cross-layer simulation platform for integration on top of the IEEE 802.16 PHY standard model, and will use Effective Capacity (EC) multi-hop model to evaluate and analyse the multi-hop end-to-end link-layer packet delay performance. We report simulation results for three-hop scenarios under different traffic load conditions and verify the efficacy of our newly developed model through comparisons to analytically derived models.

In this paper, the delay and delay-constrained throughput performance of a point-to-point wireless-powered communication system is investigated. In this system, the wireless-powered node, e.g., a user equipment (UE), receives data at the same time when powered from the other node, e.g., an access point (AP), and uses the harvested wireless energy to send data to the other node. The investigation focuses on the delay performance of sending data in the downlink (DL) from the AP node to the UE node and that in the uplink (UL) from the UE node to the AP node, based on which the throughput performance on both directions when delay constraints are enforced is also studied. To this aim, the cumulative service capacity of the service process is first analyzed for both DL and UL, taking into consideration the delay caused by the nontransmission phase for the AP or UE in each charging cycle. Thereafter, a general upper bound on the delay distribution for stochastic traffic arrivals is obtained for both DL and UL, based on which the delay-constrained throughput performance is further studied. In addition, to ensure the delay performance, the required energy storage capacity and wireless charging rate are investigated. The obtained results are exemplified with two specific traffic types, and the accuracy of the analysis is validated by comparison with extensive simulation results. The analysis and results shed new light on the performance of wireless-powered communication systems.

Delay performance of priority-queue equipped UAV-based mobile relay networks: Exploring the impact of trajectories

As the rapid development of technology, the demand to increase the network performance becomes higher. One of the parameters of a higher network performance is the increase of data rate by determining the faster and the best way for data delivery in any network. One method was used to determine that way dynamically by using OSPF and EIGRP protocol routing. Throughput, delay, jitter, packet loss, and speed performance were counted in this research. Based on the simulation using tracer packet software, the throughput was 45.75 bps, the delay was 5.91 ms, the jitter was 1.477 ms, and the loss packet was 0%. While the value of COST by data packet delivery in OSPF area was 781.25 kbps and the metric value of data packet delivery in EIGRP area was 20 kbps. With a good QoS value, the OSPF and EIGRP routing can be implemented for this network topology.

The proposed routing protocol BQAODV considers link stability, available bandwidth estimation, direction conformity and delay constraint based on AVAODV routing protocol. It selects a highest link stability route which meets available bandwidth, direction conformity and delay constraint during the search for a new route. The simulation results show that BQAODV's data packet loss rate and average end-to-end packet delay performance are better compared with AVAODV, and there is almost no difference between BQAODV's and AVAODV's average routing overhead especially under certain dynamic environment in MANET.

The exact packet loss due to buffer overflow at the transmitter side of the wireless link is derived and a closed-form approximation for the corresponding wireless effective bandwidth is obtained. This discrete fluid flow analysis (FFA) is compared with existing continuous FFA and simulation analysis. Results show that packet loss performance by the discrete FFA is more accurate than that by the continuous FFA.

This research paper presents a comparative analysis of power and delay performance between different bundled carbon nanotube (CNT) structures. An equivalent RLC model is developed for novel mixed CNT bundle structures that contains single- and multi-walled CNTs (SWCNTs and MWCNTs). Crosstalk delay and power dissipation have been compared for these proposed structures of mixed CNT bundles. It has been observed that at an average the power and delay performances are improved by 61.33% and 86.01% respectively for the novel mixed bundle structure that contains SWCNTs and MWCNTs in equal halves in comparison to bundled SWCNT.

Network high definition video applications such as video calls and videoconferences have been increasingly developed recent years. When congestions occur and network environment becomes unstable, the network applications have to deal with such issues like delay, packet loss and bandwidth constraints. In this paper, we describe a high definition H.264/AVC video transmission system with network adaptive function based on real-time transport protocol (RTP) and real-time transport control protocol (RTCP). The adaptive system is composed of three components: 1) transmission management (TM) which focuses on network state monitoring, bandwidth allocating and transmission rate control; 2) a feedback-based adaptive forward error correction (AFEC) scheme using Reed Solomon (RS) code; 3) adaptive video encoding (AVE) that adjusts the bitrate of video streaming according to the bandwidth constraint information offered by TM. In our paper, delay, packet loss and bandwidth constraints are generated by the network bottleneck and congestions. Hence, the main idea is to enhance the bitrate of video streaming adapt to the bandwidth constraints. In addition, we integrate AFEC with RTCP to feedback bandwidth status and make the adaptive video streaming more robust under packet loss environment. Here we call it interactive adaptive forward error correction (IAFEC). The test result shows IAFEC can be adaptive to strict bandwidth constraints and high packet loss rates.

The most promising technology in optical data transmission at the access network nowadays is the Ethernet passive optical network (EPON). In this paper, we study the delay performance of an intelligent fuzzy logic based dynamic bandwidth allocation (IFLDBA) algorithm for EPON. We evaluate the performance of EPONs from the simulation perspective, where IFLDBA will be compared with some other well known algorithms in terms of the packet delay and bandwidth utilization. This performance evaluation reveals that the IFLDBA shows significant improvement in terms of the packet delay and bandwidth utilization as compared to other hierarchical dynamic bandwidth allocation algorithms.

In wireless and mobile communications systems, battery power is an essential and limited resource of portable devices. Sleep mode operation is widely used to save battery power. However, by using the sleep mode, the delay in packet transmission increases. In this paper, we propose an adaptive scheme, called the p-persistent sleep decision (SD), which controls the tradeoff between the power saving and the delay performance. The proposed p-persistent SD scheme can be used for the systems adopting frame structure with fixed length. At each beginning of frame, a node decides its state (i.e., sleep or active) for the frame, according to the result of p-persistent test, considering a variety of sleep-decision parameters, for examples, the number of queued packets and the channel condition. The performance of the p-persistent SD is evaluated by using Markov analysis. Numerical results show that we can easily control the tradeoff between the power saving and the delay performance by assigning different weights to the sleep-decision parameters. As an application example, we suggest the p-persistent SD applied to IEEE 802.11 MAC and compare its performance with that of the conventional IEEE 802.11 power save mode by using simulation. The simulation results show that the proposed scheme saves more energy under the given delay constraint. Since the proposed scheme is simple and practical, it can be applied to any star- and mesh-topology wireless networks with fixed frame length.

This article presents a new paradigm for channel dynamics adaptive transmission of intermittent data in smart grid IoT communication networks, wherein novel channel prediction frameworks using stochastic modeling as well as data-driven learning of channel variability are proposed. A probing-based transmission is also proposed as a benchmark. These prediction frameworks are complemented with an adaptive channel coding scheme to increase the transmission reliability of time-critical grid monitoring data over a wireless channel. Through analyzing the prediction and packet loss performance at varying SNR and fading conditions, it is noted that the stochastic modeling framework is efficient when the fading correlation in the channel is high while the learning-based approach is more adaptive to channel dynamics as the correlation reduces. The proposed frameworks are easily implementable on low-cost end nodes, owing to the optimal selection of parameters for low runtime complexity. When compared to probing-based data transmission for a given fading in the channel, the packet loss probability of the learning-based transmission closely matches while with stochastic model loss probability is found to be 12.3% higher. However, their respective signaling overheads are 38% and 98% lower with respect to the probing-based approach, which is a significant gain at the cost of marginally additional computation complexity.

Data caching and congestion control are two strategies that can enhance the transport reliability in constrained Wireless Sensor Networks. However, these two mechanisms are designed independently for most transport protocols developed for WSN. This work developed a new cache-aware congestion control mechanism for reliable transport. RT-CaCC utilizes cache management policies such as cache insertion, cache elimination and cache size to mitigate packet losses in the network while maximizing cache utilization and resource allocation. It uses two cache management policies for packet loss detection: implicit notifications and expiration of timeout. In addition, it utilizes congestion avoidance using cache-aware rate control mechanism employing transmission window limit as a function of cache size. Results showed that the RT-CaCC obtained significant improvement gain in terms of cache utilization, end-to-end delay and throughput performance specifically during high level of packet loss in the network.

Wireless sensor networks are an emerging technology that is designed to support all types of applications. The energy constrained sensor nodes in sensor networks operate on limited batteries, so it is a very important issue to reduce energy. IEEE 802.15.4 is the best choice for the implementation of wireless sensor network. But, in high load conditions due to congestion, energy consumption is increased and throughput is reduced. To alleviate this problem existing queuing system of node is analyzed and modified in the proposed CH-MAC protocol. In this proposed algorithm hybrid MAC of CSMA and TDMA with fair share queuing system is used for better energy efficiency and improved delay performance. The method is evaluated in comparison with 802.15.4 using NS 2. Simulation results indicate improvement in packet delivery ratio, energy consumption, and delay performance.

In this paper, we first challenge the accuracy of the so-called innovative assumption that is widely adopted in delay performance analysis of network-coding-based epidemic routing (NCER) in delay-tolerant networks (DTNs). We demonstrate that this optimistic assumption severely underestimates data delivery delay and solves this problem successfully by introducing an extra encounter factor δ. Based on this, we propose a coloring process (CP)-based analytical model to evaluate the delay performance of NCER. Numerical results show that our CP-based method outperforms traditional ordinary differential equation (ODE)-based methods on estimating the delay performance under different network sizes. Furthermore, to mitigate potential competition among multiple data streams from different nodes, we propose a feedback-based recovery protocol (FRP) that takes advantage of finite buffer space and significantly reduces the number of ineffective transmissions between nodes. As a result, FRP can achieve much better delay performance compared with existing protocols in prior work.